The present invention relates generally to the field of electronic musical instruments, such as electronic organs. More specifically, the invention concerns apparatus for synchronizing the operation of two independent automatic-play features of an electronic organ such as automatic rhythm and automatic orchestration.
Automatic-play features have become extremely popular in present-day electronic organs largely as a result of the availability and widespread use of microprocessors and associated memory chips in those instruments. Through the use of a suitably programmed microprocessor and one or more associated memory chips or ROM's (read only memories), any number of sophisticated automatic-play features may be conveniently implemented in a relatively low cost organ, a feat which would have been economically prohibitive if not practically impossible in even the most expensive pre-microprocessor electronic organs. The provision of such plural automatic-play features however, introduces certain new problems which must be considered by the organ designer and resolved in a manner so as to preserve the musical integrity of the instrument. The invention described herein concerns one such problem; namely, establishing the musical integrity of a microprocessor-based electronic organ by insuring the synchronous operation of independent automatic rhythm and orchestration features regardless of the order in which those features are selected for playing.
An automatic rhythm feature may be implemented in a microprocessor-based electronic organ as generally disclosed in U.S. Pat. No. 4,242,936. The automatic rhythm feature disclosed in this patent employs a rhythm ROM which is programmed for storing at each of a plurality of consecutive memory locations a rhythm beat instruction together with an associated timing or skip instruction defining the number of clock intervals before the next beat instruction is to be addressed. The rhythm pattern stored in the ROM may be, for example, two bars in length or, stated otherwise, the number of memory locations multiplied by the cumulative total of the stored skip instructions.
Automatic orchestration or music style features, see for example copending application Ser. No. 307,161, filed Sept. 30, 1981, entitled Orchestral Accompaniment Techniques (continuation of application Ser. No. 3,584 filed Jan. 15, 1979) are in some respects typically implemented in an analagous manner in that a ROM, in this case a music style ROM, is programmed for storing at each of a plurality of consecutive memory locations a particular music style instruction. As the consecutive memory locations are sequentially addressed, the music style instrumentation circuits of the organ are operated for producing an output tone signal having a desired musical style. The musical style pattern stored in the ROM may also be, for example, two bars in length.
Each of these automatic features, i.e. automatic rhythm and automatic orchestration or musical style, are independent of each other and may be individually played without concern of the other. However, it has been found that when both are attempted to be played simultaneously, the most musically pleasing effect results when the two features operate in a synchronous or musically compatible manner. More specifically, it has been found that where both the stored rhythm pattern and the stored musical style pattern are equal in length, two bar patterns for example, and both are being played at the same time, the most musically pleasing effect occurs when both ROM's are being addressed in synchronism. That is, the most musically pleasing effect occurs when the two-bar rhythm and music style patterns are derived from the memories in time coincidence such that the first memory locations of the two ROM's are addressed at the same time. Similarly, both final memory locations should also be addressed at the same time. While such synchronous operation of the two ROM's may be conviently realized by initiating the playing of both the automatic rhythm and music style features at precisely the same point in time, it is frequently desired to initiate one of the features after the other has been in operation for some time. In this case, the two features will be played asynchronously thereby creating an undesired musical effect unless steps are taken to re-synchronize the addressing of the two ROM's.
It is therefore a basic object of the present invention to provide an electronic musical instrument having plural automatic-play features which may be simultaneously operated to produce a desired musical effect.
It is a more specific object of the invention to provide an electronic musical instrument having at least two memories each storing an independent automatic-play feature pattern of predetermined equal lengths and a system for maintaining synchronism between the two features regardless of the order in which they are operated.
These and other objects are achieved according to the invention by operating both an automatic rhythm and an automatic music style feature in response to a common clock signal. Both features, when initiated, produce two-bar musical patterns. The states of a rhythm counter clocked by the clock signal are decoded for generating a first control code tracking the extent of completion of the two-bar automatic rhythm pattern, the first control code being used to initialize start-up of the music style pattern during a performance of the automatic rhythm feature to insure completion of the two musical patterns in time coincidence. A second control code is calculated in response to the clock signal to initialize start-up of the automatic rhythm pattern during a performance of the music style feature to insure completion of the two musical patterns in time coincidence.